Performance Simulation of a Double Tube Heat Exchanger Based on Different Nanofluids by Aspen Plus

A heat exchanger’s performance depends heavily on the operating fluid’s transfer of heat capacity and thermal conductivity.Adding nanoparticles of high thermal conductivity materials is a significant way to enhance the heat transfer fluid’s thermal conductivity.This research used engine oil containing alumina(Al_(2)O_(3))nanoparticles and copper oxide(CuO)to test whether or not the heat exchanger’s efficiency could be improved.To establish the most effective elements for heat transfer enhancement,the heat exchangers thermal performance was tested at 0.05%and 0.1%concentrations for Al_(2)O_(3)and CuO nanoparticles.The simulation results showed that the percentage increase in Nusselt number(Nu)for nanofluid at 0.05%particle concentration compared to pure oil was 9.71%for CuO nanofluids and 6.7%for Al_(2)O_(3)nanofluids.At 0.1%concentration,the enhancement percentage in Nu was approximately 23%for CuO and 18.67%for Al_(2)O_(3)nanofluids,respectively.At a concentration of 0.1%,CuO nanofluid increased the LMTD and overall heat transfer coefficient(U)by 7.24 and 5.91%respectively.Both the overall heat transfer coefficient(U)and the heat transfer coefficient(hn)for CuO nanofluid at a concentration of 0.1%increased by 5.91%and 10.68%,respectively.The effectiveness(εn)of a heat exchanger was increased by roughly 4.09%with the use of CuO nanofluid in comparison to Al_(2)O_(3)at a concentration of 0.1%.The amount of exergy destruction in DTHX goes down as Re and volume fractions go up.Moreover,at 0.05%and 0.1%nanoparticle concentrations,the percentage increase in dimensionless exergy is 10.55%and 13.08%,respectively.Finally,adding the CuO and Al_(2)O_(3)nanoparticles improved the thermal conductivity of the main fluid(oil),resulting in a considerable increase in the thermal performance and rate of heat transfer of a heat exchanger.

An advanced turbulator with blades and semi-conical section for heat transfer improvement in a helical double tube heat exchanger

In present work,a helical double tube heat exchanger is proposed in which an advanced turbulator with blades,semi-conical part,and two holes is inserted in inner section.Two geometrical parameters,including angle of turbulator’s blades(θ) and number of turbulator’s blades(N),are considered.Results indicated that firstly,the best thermal stratification is achieved at θ=180°.Furthermore,at the lowest studied mass flow rate(m = 8 × 10^(-3) kg/s),heat transfer coefficient of turbulator with blade angle of 180° is 130.77%,25%,and 36.36% higher than cases including without turbulator,with turbulator with blade angle of θ =240°,and θ =360°,respectively.Moreover,case with N=12 showed the highest overall performance.At the highest studied mass flow rate(m = 5.842 × 10^(-2) kg/s),heat transfer coefficient for case with N=12 is up to 54.76%,27.45%,and 6.56% higher than cases including without turbulator,with turbulator with N=6,and with turbulator with N=9,respectively.

Effect of Empowering Education on Refined Nursing of Patients with Internal Double J Tubes after Surgery for Ureteral Stricture

Objective: To investigate the effect of the theory of enabling education on the fine management of patients with internal double J tubes after ureteral stricture. Methods: Eighty patients with built-in double J tubes after ureteral stricture were selected from the urology department of a grade a hospital in Guangzhou. The patients were divided into control group and observation group by random number method, with 40 patients in each group. The control group received refined nursing after surgery, while the observation group received refined nursing including the theory of empowerment education after surgery on the basis of the control group. Results: After the intervention, the observation group had a higher standard rate of quality indicators, higher self-efficacy score than the control group (P ≤ 0.05), lower scores of ureteral stent-related symptoms, urinary system symptoms, pain symptoms, total health status, job performance, additional problems and total scores than the control group (P ≤ 0.05), and statistically significant differences were found in the total health status dimension and total scores (P ≤ 0.01). The nursing satisfaction survey, the scores of clinical nursing, health education, psychological counseling and nurse-patient communication were all higher than those in the control group (P ≤ 0.05), and the differences in health education and nurse-patient communication were statistically significant (P ≤ 0.01). Conclusion: The theory of enabling education can improve patients’ self-nursing level, promote the implementation of refined nursing quantitative indicators and nursing measures, relieve the poor symptoms of ureteral stricture patients, and improve patients’ satisfaction with nursing work.

Numerical and experimental study of an innovative pipeline design in a granular pneumatic-conveying system

During gas-solid mixture conveying in a dense phase, material is conveyed in dunes on the bottom of the pipeline, or as a pulsating moving bed. This phenomenon increases the pressure drop and power consumption. We introduce a new technique to reduce the pressure drop, which is termed the perforated double tube. To validate this new model, the gas-solid flow pattern and pressure drop were studied numerically and experimentally. The power consumption was also studied experimentally. Numerical studies were performed by the Eulerian-Lagrangian approach to predict gas and particle movement in the pipeline, Comparisons between the numerical predictions and the experimental results for the gas-solid flow patterns and pressure drop show good agreement.

Characterization of a-Si:H/SiN multilayer waveguide polarization using an optical pumping application—LED

This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its surface.By using double tubed coaxial line(DTCL) microwave plasma chemical vapor deposition(MPCVD) equipment,an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer order.The main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon nitrate.Once the sample was ready,another major objective of the experiment was to analyze the polarization characteristics of the fabricated waveguide.The idea of the experiment was to analyze how the waveguide reacts when three types of LED(blue,yellow,and red) are radiated onto its surface.The results showed that the fabrication of the a-Si:H/SiN sample is successful.Most effective transmission results,which accord with the polarization characteristics analysis,were obtained.